In a bowl mix together 1 C. cocoa powder (Iprefer Scharffen Berger unsweetened and not dutched) with 2 C. a.p. flour 1/2 tsp. baking powder (Rumford if you can get it no aluminum taste and has the highest carbon dioxide yield) 1 tsp. salt and 2 tsp. instant espresso powder mix it all well.
In the bowl of a stand mixer beat 3 sticks butter on high until light and fluffy. Gradually beat in 3 C. granulated sugar then turn to high speed and beat 5 minutes. Add 2 tsp. vanilla and then 5 lg. eggs, adding them one at a time.
Combine 1 C. butter milk with 1/4 C.water.
With the mixer running on low gradually add in the flour cocoa mixture alternating with the buttermilk/water mixture. Combine all well and pour into a 10" bundt/tube pan rapping on the counter to help settle the batter. Bake at 325 F until a cake tester come out clean.
It took about and hour and 40 minutes today, I have had it be done in and hour and a half too. Just depends I guess. I also watch it and often find that I need to lay a square of foil on top for the last half hour to fourty-five minutes. Cool it in the pan well before turning out on a rack to finish cooling then wrap well in plastic. It will keep for a week. It serves 16 and you really don't want big pieces, it is very rich and flavor dense.